1. Field of Invention
The present invention relates to a ball valve and more particularly, to a ball valve having a hemispherical plug in which a suitable hole is defined for communicating with connector holes defined in the casing and the plug having sealing elements disposed thereto for sealing the connector holes when rotating the plug.
2. Related Prior Art
In the case of so-called "top entry" ball valves, the housing is sealed by means of a flange and a plurality of screws for holding the plug of the cock, in order to create an opening for installing the plug of the cock which also enables the plug of the cock and seals to be removed after such a ball valve has been welded in as a part of a duct.
A ball valve has come to light from DE 39 14 327 which has a cover on the housing. The housing contains two lockable conduits running in parallel which are assigned a rotating, hemispherical plug running on bearings in the housing. This closes the housing with the plug by means of the cover for the plug for guiding the actuating mechanism. Sealing rings are fitted coaxially in extended recesses of the conduits; these are in the immediate area of the holes in the ball.
A ball valve has come to light from G 94 08 156 in which a single-piece sealer which forms a seal by supporting itself on the walls of the hollow space in the housing and which has a hemispherical recess for the plug of the cock as well as coaxial holes with coaxial connector holes. The sealer is made from a suitable material and completely covers the hollow space in the valve housing, so that the medium traveling through the valve cannot be held back in crevices or other dead spaces. This is further improved by the fact that the cover helps to press the sealer tightly into the hollow space by means of preliminary tension at the plug of the cock. This prevents the product from getting into the hollow space between the cover and plug, for example. A ball valve with this structure functions satisfactorily. However if the seal becomes damaged, it is necessary to replace the complete cladding formed by the sealer. This involves not inconsiderable expense, particularly if the sealer is to be made from high-grade material.
For this reason the purpose of the invention is to provide a weldable ball valve which enables the plug of the cock and the sealant to be installed and removed, which has no crevices or dead spaces where the product can stick, and which can be manufactured with the lowest possible expenditure on production and materials.